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Updated: Sep 9, 2025

Spectral and Angle-Resolved Magneto-Optical Characterization of Photonic Nanostructures
Published on: November 21, 2019
Unidirectional perfect absorption induced by chiral coupling in spin-momentum locked waveguide magnonics
Jie Qian1,2, Qi Hong1, Zi-Yuan Wang1
1Zhejiang Key Laboratory of Micro-Nano Quantum Chips and Quantum Control, State Key Laboratory for Extreme Photonics and Instrumentation, School of Physics, Zhejiang University, Hangzhou, China.
None:
Chiral coupling offers alternative avenues for controlling and exploiting light-matter interactions. We demonstrate that chiral coupling can be utilized to achieve unidirectional perfect absorption. In our experiments, chiral magnon-photon coupling is realized by coupling the magnon modes in yttrium iron garnet (YIG) spheres with spin-momentum-locked waveguide modes supported by spoof surface plasmon polaritons (SSPPs). These photon modes exhibit transverse spin, with the spin direction determined by the propagation direction. Due to the intrinsic spin properties of the magnon mode, it exclusively couples with microwaves traveling in one direction, effectively suppressing the reflection channel. Under the critical coupling condition, transmission is also eliminated, resulting in unidirectional perfect absorption. By incorporating additional YIG spheres, bidirectional and multi-frequency perfect absorption can be achieved. Our work introduces a functional platform for exploring and harnessing chiral light-matter interactions within spin-momentum locked devices, offering a paradigm for unidirectional signal processing and energy harvesting technologies.
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